1. Field of the Invention
The present invention relates to an electrical joystick controller.
2. State of the Art
It is sometimes required that, when the joystick control lever reaches a predetermined position after displacement along one of its major axes, that it can be displaced further in the same direction but only upon application of a significantly increased force (i.e. the operator experiences significantly increased resistance when moving the control lever beyond the predetermined position). In one known joystick controller, this is achieved in that a bush, carried on the joystick lever and spring-biased against a fixed cam surface, reaches a more steeply-inclined portion of the cam surface. A problem with this is that the position of the joystick lever, along the respective major axis, at which the bush engages the steeper portion of the cam, tends to vary according to the position of the joystick lever along its other, orthogonal major axis. Thus, the electrical signal from the joystick transducer arrangement for the one major axis, at which the increased resistance takes effect, varies depending on the position of the joystick lever along the other major axis. This is a problem for example where a threshold level of that signal is to be used to indicate that the operator has effected the additional displacement of the joystick lever, in order to initiate a particular control function of the apparatus or machine being controlled by the joystick device.
We have now devised a joystick controller which overcomes the above problem.